JP2023175149A - Photoreceiver - Google Patents

Abstract

To provide a photoreceiver capable of reducing reflected return light.SOLUTION: A photoreceiver according to one embodiment includes: a first collimator lens that has an incident lens subjected to incidence of first collimator light with a predetermined diameter, and an outgoing lens emitting second collimator light with a diameter smaller than the predetermined diameter by receiving light entering the incident lens and spreading out from a light-concentrated focus; and a light receiving element that has a light receiving lens where the second collimator light enters and the second collimator light is emitted as converging rays, and a light receiving section for receiving the converging rays from the light receiving lens.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to optical receivers.

Patent Document 1 describes an optical receiving module. The optical receiving module includes a receptacle section and a package section. The receptacle portion has a first lens that receives light from the optical fiber. The package part includes an optical demultiplexer that receives the light from the first lens, a reflector that reflects the light split by the optical demultiplexer, and a second lens that receives the light reflected by the reflector. has. The optical receiving module further includes a light receiving element, and the light receiving element receives the light focused by the second lens.

Patent Document 2 describes an optical receiving module and a method for manufacturing the same. The optical receiving module has a package part, and an optical demultiplexer, a reflector, a condensing lens, and a light receiving element are arranged inside the package part. The light split by the optical splitter enters the reflector and is reflected by the reflector. The light reflected by the reflector is condensed by a condensing lens and enters the light receiving element.

Patent Document 3 describes a wavelength multiplexing optical receiving module. The wavelength multiplexed optical receiver module includes a collimating lens that converts input light into collimated light, a wavelength division filter that splits the collimated light into multiple signal lights based on the wavelength, and a mirror that reflects the split signal lights. . The wavelength multiplexed optical receiving module further includes a lens array having a condenser lens that condenses the signal light reflected by the mirror, and a PD (Photo Diode) that receives the condensed signal light.

Japanese Patent Application Publication No. 2013-125045 Japanese Patent Application Publication No. 2014-137476 Japanese Patent Application Publication No. 2017-32731

In the above-mentioned optical receiver module, the light that passes through the optical receptacle connected to the optical fiber is converted into collimated light by the collimating lens, and the signal light for each wavelength is converted by the optical demultiplexer having optical filters and mirrors corresponding to each wavelength. separated into Each separated signal light is reflected by a mirror, then condensed by a lens array, and reaches a light receiving element.

In order to satisfy the desired photoelectric conversion characteristics in the light receiving element, it is required that each component be arranged with precision and optically coupled to the light receiving element with low loss. However, simply arranging each component accurately may result in the amount of reflected light returning from the lens on the surface of the light receiving element exceeding a predetermined amount. Therefore, it is required to reduce the reflected return light while maintaining the characteristics of light receiving sensitivity to the light receiving element.

The present disclosure aims to provide an optical receiver that can reduce reflected return light.

The optical receiver according to the present disclosure includes an input lens into which a first collimated light having a predetermined diameter is incident, and a first collimated light having a diameter smaller than the predetermined diameter by receiving the light which is incident on the input lens and spreads from a focused focal point. a first collimating lens having an output lens that emits a second collimated light, a light receiving lens that receives the second collimated light and emits the second collimated light as a focused light, and receives the focused light from the light receiving lens. A light receiving element having a light receiving section.

According to the present disclosure, reflected return light can be reduced.

FIG. 2 is a cross-sectional view showing the internal structure of the optical receiver according to the embodiment. 2 is a diagram showing a first collimating lens and a light receiving element of the optical receiver of FIG. 1. FIG. FIG. 3 is a diagram showing the first collimating lens of FIG. 2; FIG. 3 is a diagram showing the output lens of the first collimating lens and the light receiving lens of the light receiving element in FIG. 2; It is a figure which shows the 1st collimating lens of the optical receiver based on the 1st modification. It is a figure showing the optical receiver concerning the 2nd modification. It is a figure showing the optical receiver concerning the 3rd modification.

[Description of embodiments of the present disclosure]
First, the contents of the embodiment of the optical receiver according to the present disclosure will be listed and explained. (1) An optical receiver according to an embodiment includes an entrance lens into which a first collimated light having a predetermined diameter is incident, and a first collimated light having a predetermined diameter after receiving the light that is incident on the input lens and spread from a focused focal point. a first collimating lens having an output lens that outputs a second collimated light having a smaller diameter; a light receiving lens that receives the second collimated light and emits the second collimated light as a focused light; and a light receiving element having a light receiving section that receives the focused light.

This optical receiver includes a first collimating lens having an entrance lens and an exit lens, and a light receiving element having a light receiving lens and a light receiving section. The input lens converts the incident first collimated light into focused light, and the light that spreads from the focal point of the focused light is converted into second collimated light by the output lens. The diameter of the second collimated light is smaller than the diameter of the first collimated light. The light receiving lens of the light receiving element receives not the focused light but the second collimated light. Therefore, when the light receiving lens receives the second collimated light having a smaller diameter than the first collimated light, the reflected return light from the light receiving lens can be reduced. Therefore, it is possible to prevent the reflected return light from the light-receiving lens, which is the surface of the light-receiving element, from exceeding a predetermined amount of light, so that the reflected return light can be reduced while maintaining the characteristics of light-receiving sensitivity to the light-receiving element.

(2) In (1) above, the first collimating lens has a reflective surface therein, and the reflective surface is provided between the incident lens and the focal point, and vertically reflects the first collimated light to form the second collimated light. It may also emit light.

(3) In (1) or (2) above, the optical receiver includes a second collimating lens that emits the first collimated light incident on the first collimating lens, and a space between the first collimating lens and the second collimating lens. and an optical demultiplexer provided.

(4) In (3) above, the first collimating lens and the second collimating lens are an integrated lens unit, and in the lens unit, a recess is provided between the first collimating lens and the second collimating lens, and the The duplexer may be placed at the bottom of the recess. In this case, since the optical receiver includes a lens unit in which the first collimating lens and the second collimating lens are integrated, the parts of the optical receiver can be assembled easily and with high precision. Furthermore, the optical components including the optical demultiplexer provided between the first collimating lens and the second collimating lens can be mechanically aligned without alignment.

(5) In (3) above, the output side end face of the second collimating lens and the end face of the optical demultiplexer may be bonded to each other via an adhesive.

(6) In any one of (1) to (5) above, the curvature of the light receiving lens may be larger than the curvature of the output lens of the first collimating lens.

[Details of embodiments of the present disclosure]
A specific example of an optical receiver according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to the following examples, but is indicated in the claims, and is intended to include all changes within the scope of equivalency to the claims. In the description of the drawings, the same or corresponding elements are given the same reference numerals, and redundant description will be omitted as appropriate. In addition, some parts of the drawings may be simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

FIG. 1 is a diagram showing a cross section of an optical receiver 1 according to an embodiment. FIG. 1 is a diagram schematically showing a cross section of the optical receiver 1, and some parts mounted on the optical receiver 1 are not shown. The optical receiver 1 receives a wavelength multiplexed optical signal in which a plurality of signal lights having a plurality of different wavelengths (for example, λ ₁ to λ ₈ ) are multiplexed. The optical receiver 1 demultiplexes the received wavelength-multiplexed optical signal into a plurality of signal lights and outputs electrical signals corresponding to each signal light. The optical receiver 1 includes a receptacle section 10, a package section 20, and a terminal section 30.

In the following, for convenience, the direction in which the receptacle part 10 is viewed from the package part 20 is referred to as "front", "front side", or "front", and the direction in which the package part 20 is viewed from the receptacle part 10 is referred to as "rear", "rear". It is explained as "side" or "rear". However, these directions are for convenience of explanation, and do not limit the arrangement positions of the components.

The receptacle section 10 couples, for example, a single mode optical fiber. The receptacle section 10 includes a sleeve 11 into which a ferrule of an external optical connector of the optical receiver 1 is inserted, a holder 12 that joins the receptacle section 10 to a package section 20, and a joint sleeve 13 that connects the sleeve 11 and the holder 12 to each other. and has.

The package section 20 accommodates an optical component and a light receiving element that receives light that has passed through the optical component. For example, the package portion 20 has a rectangular parallelepiped shape. The package section 20 includes, for example, a package frame 21, a bottom wall 22, and a lid 23. The package frame 21 has a rectangular tube shape. The bottom wall 22 constitutes the bottom of the package section 20. Bottom wall 22 includes, for example, copper molybdenum or copper tungsten. Since copper molybdenum and copper tungsten have high thermal conductivity, when the bottom wall 22 includes copper molybdenum or copper tungsten, the heat dissipation performance of the bottom wall 22 can be improved.

The lid body 23 is provided to close an opening formed in the upper part of the package frame 21. After the components of the optical receiver 1 are arranged and wired inside the package frame 21, the lid body 23 is fixed to the package frame 21 so as to seal the internal space S of the package section 20. The package part 20 has a bush 24, for example. The bush 24 has an annular shape. The front-facing surface of the bush 24 is flat.

The terminal section 30 is provided for electrical connection of the optical receiver 1 with an external circuit of an external device. The terminal section 30 includes, for example, a plurality of stacked ceramic substrates. The terminal portion 30 is fixed to the package portion 20 while being fitted into the wall portion 21b of the package frame 21. The terminal section 30 electrically connects an element inside the package section 20 and a device outside the optical receiver 1 to each other. The terminal section 30 has a high frequency line and a power line.

The holder 12 of the receptacle section 10 is fixed to the package section 20 via a bush 24. The sleeve 11 is coupled to the holder 12 via a joint sleeve 13. The joint sleeve 13 performs centering in the axial direction (the left-right direction in FIG. 1) and the radial direction (the vertical direction in FIG. 1, and the direction orthogonal to the plane of the paper in FIG. 1).

The receptacle portion 10 includes, for example, a stub 14. The stub 14 is located inside the sleeve 11. As described above, the ferrule of an external optical connector is inserted into the sleeve 11, and the ferrule holds an external optical fiber. This external fiber is optically coupled to the optical fiber 15 held by the stub 14. The receptacle part 10 has a lens 16 arranged inside the holder 12. The lens 16 converts the light emitted from the optical fiber 15 into, for example, collimated light. A wavelength-multiplexed signal light is emitted from the lens 16, and the wavelength-multiplexed signal light is emitted into the package section 20 through an optical window sealed in the bush 24.

The package section 20 includes an optical module 40 that demultiplexes the wavelength-multiplexed signal light emitted from the lens 16 into a plurality of signal lights of different wavelengths. The optical module 40 has a support substrate 41 on which the optical components of the optical receiver 1 are mounted. For example, the optical module 40 has a support member 42 , and the support substrate 41 is arranged at a position separated from the bottom wall 22 by the support member 42 . The optical components mounted on the support substrate 41 are arranged to face the bottom wall 22.

The package section 20 includes a mirror 43, a first collimating lens 50, and a light receiving element 45. Each of the plurality of signal lights demultiplexed by the optical module 40 is bent by 90 degrees at the mirror 43 and output from the mirror 43 toward the bottom wall 22 . The first collimator lens 50 includes a plurality of lenses that converge each of the plurality of signal lights. The package part 20 has a plurality of light receiving elements 45, and the signal light focused by each of the plurality of lenses is received by each light receiving element 45.

The first collimating lens 50 and the light receiving element 45 are mounted on the package section 20 via, for example, a first mounting board 46 placed on the bottom wall 22 and a second mounting board 47 placed on the first mounting board 46. ing. For example, a TIA (Trans Impedance Amplifier) 48 located between the second mounting board 47 and the terminal section 30 is mounted on the first mounting board 46 . The TIA 48 is electrically connected to the light receiving element 45 via a wire 49, for example. Below, the direction in which the light receiving element 45 is provided when viewed from the bottom wall 22 is referred to as "above", "upper side", or "upper", and the direction in which the bottom wall 22 is provided as seen from the light receiving element 45 is referred to as "lower", "lower". This is explained as "side" or "downward." However, these directions are for convenience of explanation and do not limit the directions of each part.

FIG. 2 is an enlarged view of the area of the optical receiver 1 where the mirror 43, the first collimating lens 50, and the light receiving element 45 are arranged. The optical receiver 1 further includes a first collimating lens 50 disposed between the mirror 43 and the light receiving element 45. The light (signal light) incident on the mirror 43 and the light reflected on the mirror 43 are first collimated light L1 having a predetermined diameter D1. The first collimating lens 50 receives the first collimated light L1 reflected by the mirror 43 and converts the first collimated light L1 into a second collimated light L2 having a diameter D2 smaller than a predetermined diameter D1. The first collimating lens 50 emits the second collimated light L2 toward the light receiving element 45.

The light receiving element 45 is, for example, a PD (Photo Diode). The light receiving element 45 includes a light receiving lens 45b that receives the second collimated light L2, and a light receiving section 45c that receives the light L3 focused by the light receiving lens 45b. The light receiving section 45c has, for example, a disk shape. The light receiving lens 45b is, for example, a convex lens protruding toward the first collimating lens 50, and has a curved surface facing the first collimating lens 50. The light L3 incident on the light receiving section 45c is converted into an electric signal (photocurrent) and transmitted to the TIA 48 via the wire 49 described above. For example, the second collimated light L2 from the first collimating lens 50 is perpendicularly incident on the vertex of the light receiving lens 45b.

FIG. 3 is an enlarged view of the first collimating lens 50. As shown in FIG. 3, the first collimating lens 50 includes, for example, an entrance lens 51 into which the first collimated light L1 enters, and a block 52 in which a focal point L4 formed by entering the entrance lens 51 is formed. and an output lens 53 that receives the light L5 spreading from the focal point L4 and converts the light L5 into the second collimated light L2.

The entrance lens 51 is a convex lens that protrudes toward the mirror 43 and has a curved surface facing the mirror 43. The block 52 has, for example, a rectangular parallelepiped shape. The block 52 has a first surface 52b on which an input lens 51 is formed, and a second surface 52c facing opposite to the first surface 52b, and an output lens 53 is formed on the second surface 52c. The block 52 transmits the light L6 collected by the input lens 51, the focal point L4 of the light L6, and the light L5 spreading from the focal point L4. The output lens 53 is a convex lens that protrudes toward the light receiving element 45 and has a curved surface facing the light receiving element 45. The output lens 53 converts the light L5 into second collimated light L2, and outputs the converted second collimated light L2 to the light receiving element 45.

The effects obtained from the optical receiver 1 according to this embodiment will be described above. The optical receiver 1 includes a first collimating lens 50 having an entrance lens 51 and an exit lens 53, and a light receiving element 45 having a light receiving lens 45b and a light receiving section 45c. The input lens 51 converts the incident first collimated light L1 into a focused light L6, and the light L5 spreading from the focal point L4 of the light L6 is converted by the output lens 53 into a second collimated light L2. The diameter D2 of the second collimated light L2 is smaller than the diameter D1 of the first collimated light L1. The light receiving lens 45b of the light receiving element 45 receives not the focused light but the second collimated light L2.

Therefore, as shown in FIG. 4, when the light receiving lens 45b receives the second collimated light L2 having a smaller diameter than the first collimated light L1, the reflected return light L7 from the light receiving lens 45b can be reduced. Therefore, it is possible to prevent the reflected return light L7 from the light receiving lens 45b, which is the surface of the light receiving element 45, from exceeding a predetermined amount of light, so that the reflected return light L7 can be reduced while maintaining the characteristics of the light receiving sensitivity to the light receiving element 45. I can do it. More specifically, the amount of reflected return light L7 can be reduced to 1/1000 or less of the second collimated light L2.

Next, an optical receiver according to a first modification will be described with reference to FIG. 5. The optical receiver according to the first modification includes a first collimating lens 50A different from the first collimating lens 50 described above. In the following, descriptions that overlap with the description of the optical receiver 1 described above will be given the same reference numerals and omitted as appropriate.

The first collimating lens 50A includes an input lens 51 into which the first collimated light L1 enters, a block 57 different from the block 52 described above, and an output lens 58 different from the output lens 53 described above. As shown in FIGS. 3 and 5, for example, the length A1 of the block 52 in the optical axis direction, which is the direction in which the optical axis X of the first collimated light L1 extends, is the length A1 of the block 52 in the direction perpendicular to the optical axis. The length is shorter than A2. On the other hand, the length A3 of the block 57 in the optical axis direction is longer than the length A4 of the block 57 in the direction perpendicular to the optical axis. Furthermore, length A3 is longer than length A1.

For example, the curvature of the output lens 53 is larger than the curvature of the light receiving lens 45b of the light receiving element 45. The material of the exit lens 53 is, for example, resin or silicon. The curvature of the output lens 58 is smaller than the curvature of the light receiving lens 45b of the light receiving element 45. That is, in the first modification, the curvature of the light receiving lens 45b is larger than the curvature of the output lens 58 of the first collimating lens 50A. Note that it is desirable that the inclination angle (mounting angle) of each of the output lens 53 and the output lens 58 with respect to the optical axis X is suppressed to ±0.3° or less.

Next, an optical receiver 61 according to a second modification will be described with reference to FIG. 6. FIG. 6 is a diagram schematically showing a partial configuration of the optical receiver 61. As shown in FIG. As shown in FIG. 6, the optical receiver 61 has an optical module 70 that is different from the optical module 40. The optical module 70 includes a support substrate 71 arranged at a position separated from the bottom wall 22, and a first collimator lens 72, a second collimator lens 73, and an optical demultiplexer 74 mounted on the support substrate 71. The first collimating lens 72 is located above the light receiving element 45, and the second collimating lens 73 is located behind the receptacle portion 10. The optical demultiplexer 74 is provided between the first collimating lens 72 and the second collimating lens 73.

The first collimating lens 72 includes an input lens 72b into which the first collimated light L1 enters, a block 72c in which a focal point L4 is formed, an output lens 72d which converts the light L5 into a second collimated light L2, and an input lens. It includes a reflective surface 72f that reflects the light L6 from 72b toward the exit lens 72d. The reflective surface 72f vertically reflects the first collimated light L1 and emits the second collimated light L2. More specifically, the reflective surface 72f bends the light L6 emitted backward from the incident lens 72b by 90 degrees and emits the light L6 downward. A focal point L4 of the light L6, which is the focused light, is formed below the reflective surface 72f. Then, the light L5 that spreads downward from the focal point L4 enters the output lens 72d, and the output lens 72d converts the light L5 into second collimated light L2 and outputs the second collimated light L2 toward the light receiving element 45. .

The second collimating lens 73 includes, for example, an input lens 73b into which the diverging light L9 from the receptacle part 10 enters and converting the divergent light L9 into the first collimated light L1, and a block 73c provided with the input lens 73b. . The first collimated light L1 is emitted from the input lens 73b, and the first collimated light L1 emitted from the input lens 73b passes through the block 73c and reaches the optical demultiplexer 74. The optical demultiplexer 74 demultiplexes the first collimated light L1, and each of the first collimated lights L1 demultiplexed by the optical demultiplexer 74 enters the first collimating lens 72. As described above, the optical receiver 61 according to the second modification is arranged between the second collimating lens 73 that emits the first collimated light L1 that is incident on the first collimating lens 72, and the space between the first collimating lens 72 and the second collimating lens 73. An optical demultiplexer 74 provided in the optical demultiplexer 74 is provided. This optical receiver 61 also provides the same effects as the optical receiver 1 described above. The block 73c and the optical demultiplexer 74 are bonded via adhesive. That is, the output side end face of the second collimating lens 73 and the input side end face of the optical demultiplexer 74 are bonded to each other via an adhesive. In this case, return light can be suppressed.

Next, an optical receiver 81 according to a third modification will be described with reference to FIG. 7. FIG. 7 is a diagram schematically showing the configuration of a part of the optical receiver 81. As shown in FIG. 7, the optical receiver 81 has an optical module 90 that is different from the optical module 70 described above. The optical module 90 includes an optical demultiplexer 74 and a lens unit 91 in which the first collimating lens 72 and the second collimating lens 73 described above are integrated.

For example, the lens unit 91 has a recess 92 located between the first collimating lens 72 and the second collimating lens 73, and the optical demultiplexer 74 is disposed in the recess 92. That is, in the lens unit 91, a recess 92 is provided between the first collimating lens 72 and the second collimating lens 73, and the optical demultiplexer 74 is disposed at the bottom of the recess 92. The recess 92 is defined by the entrance lens 72b of the first collimating lens 72, the block 73c of the second collimating lens 73, and a bottom surface 92b extending from the block 73c to the entrance lens 72b. Placed. The lens unit 91 has a block portion 93 mounted on the bottom wall 22. A second collimating lens 73 is provided on the front side and above the block part 93, and a first collimating lens 72 is provided on the rear side and above the block part 93.

As described above, in the optical receiver 81 according to the third modification, the first collimating lens 72 and the second collimating lens 73 are integrated into the lens unit 91. Since the optical receiver 81 includes the lens unit 91 in which the first collimating lens 72 and the second collimating lens 73 are integrated, the parts of the optical receiver 81 can be assembled easily and with high precision. Furthermore, the optical components including the optical demultiplexer 74 provided between the first collimating lens 72 and the second collimating lens 73 can be mechanically aligned without alignment.

The embodiments and various modifications of the optical receiver according to the present disclosure have been described above. However, the present invention is not limited to the embodiment or each modification described above. Those skilled in the art will readily recognize that various modifications and changes can be made to the present invention without departing from the gist of the invention as set forth in the claims. For example, the shape, size, number, material, and arrangement of each component of the optical receiver are not limited to those described above and can be changed as appropriate.

For example, in the embodiment described above, the receptacle section 10 includes the sleeve 11, the holder 12, the joint sleeve 13, the stub 14, the optical fiber 15, and the lens 16. However, the configuration of the receptacle section of the optical receiver is not limited to the above example and can be modified as appropriate. The structure of the package part and the structure of the terminal part are not limited to the above-mentioned examples, but can be changed as appropriate.

1... Optical receiver 10... Receptacle part 11... Sleeve 12... Holder 13... Joint sleeve 14... Stub 15... Optical fiber 16... Lens 20... Package part 21... Package frame 21b... Wall part 22... Bottom wall 23... Lid body 24 ...Bush 30...Terminal portion 40...Optical module 41...Support substrate 42...Support member 43...Mirror 45...Light receiving element 45b...Light receiving lens 45c...Light receiving portion 46...First mounting board 47...Second mounting board 48...TIA
49... Wires 50, 50A... First collimating lens 51... Incoming lens 52... Block 52b... First surface 52c... Second surface 53... Outgoing lens 57... Block 58... Outgoing lens 61... Optical receiver 70... Optical module 71... Support substrate 72...First collimating lens 72b...Incoming lens 72c...Block 72d...Outgoing lens 72f...Reflecting surface 73...Second collimating lens 73b...Incoming lens 73c...Block 74...Optical demultiplexer 81...Optical receiver 90...Optics Module 91...Lens unit 92...Concave portion 92b...Bottom surface 93...Block portions D1, D2...Diameters L3, L5, L6, L7...Light L1...First collimated light L2...Second collimated light L4...Focus L9...Divergent light S... Internal space X…optical axis

Claims (6)

an input lens into which a first collimated light beam having a predetermined diameter is incident; and a second collimated light beam having a diameter smaller than the predetermined diameter is emitted upon receipt of light that is incident on the input lens and spreads from a focused focal point. a first collimating lens having an exit lens;
a light-receiving element having a light-receiving lens into which the second collimated light is incident and which emits the second collimated light as focused light; and a light-receiving section that receives the focused light from the light-receiving lens;
optical receiver. The first collimating lens has a reflective surface therein,
The reflective surface is provided between the incident lens and the focal point, and vertically reflects the first collimated light and emits the second collimated light.
The optical receiver according to claim 1. a second collimating lens that emits the first collimated light that is incident on the first collimating lens;
an optical demultiplexer provided between the first collimating lens and the second collimating lens,
The optical receiver according to claim 1 or claim 2. The first collimating lens and the second collimating lens are an integrated lens unit,
In the lens unit, a recess is provided between the first collimating lens and the second collimating lens,
the optical demultiplexer is disposed at the bottom of the recess;
The optical receiver according to claim 3. The exit side end face of the second collimating lens and the input side end face of the optical demultiplexer are bonded to each other via an adhesive.
The optical receiver according to claim 3. The curvature of the light receiving lens is larger than the curvature of the output lens of the first collimating lens.
The optical receiver according to claim 1 or claim 2.

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